The present invention relates to a retractor for a seat belt, and more particularly relates to a retractor having a clamping mechanism which directly pinches a webbing as a seat belt at the time of an emergency so as to clamp the webbing to minimize the pulled-out length thereof from the retractor.
A seat belt device for safely keeping an occupant on the seat of a vehicle or the like includes a webbing as a seat belt, a buckle, fasteners, and a retractor which automatically pulls the webbing into the retractor and winds the webbing when the device is not in use. The retractor functions so that the webbing is protected from damage and that the pulled-out length of the webbing from the retractor can be optionally altered when the seat belt device is in use.
Such retractors include an automatic-locking retractor, an emergency-locking retractor and the like. The emergency-locking retractor is generally used in order to avoid the problem of excessively restraining an occupant to give him a feeling of pressure. For that purpose, an emergency locking mechanism having an inertia sensor which reacts to a sharp acceleration, a collision, a sharp deceleration or the like to physically lock the winding shaft of the emergency-locking retractor to keep the shaft from rotating in such a direction as to allow a webbing as a seat belt to be pulled out of the retractor is provided therein to effectively and safely restrain the occupant and reduce his feeling of pressure of the webbing. Even when the seat belt device having the emergency-locking retractor is in use, the webbing remains wound by a relatively large length around the winding shaft of the retractor so as to be tightened on the webbing itself due to the tension thereof. For that reason, the webbing unwinds out of the retractor at the time of an emergency although the winding shaft is locked at that time not to rotate in such a direction as to allow the webbing to be pulled out of the retractor. This is a problem. Since such unwinding deteriorates the occupant restraining function of the retractor, the unwinding needs to be minimized.
Accordingly, various retractors each including a clamping mechanism which directly pinches a webbing at the outlet opening of the retractor to minimize the unwinding of the webbing have been proposed. For such a clamping mechanism, there is a manner of pinching a webbing between a guide roller on which the webbing is wound to be guided by the roller, and a clamping member secured to a base. However, the manner has a drawback that since it is complicated to lay the webbing around in the retractor, it does not feel good to either pull the webbing into the retractor to wind the webbing therein, or pull it out of the retractor to unwind the webbing therein.